load introduction into aerospace structures€¦ · load introduction into aerospace structures ......

Load Introduction into Aerospace Structures Dr. Tamas Havar,

Airbus Group Innovations

Symposium 5th anniversary of Institute of Carbon Composites

POC: [email protected]

Introduction

11.09.2014 2

Airbus Group Innovations – Tamas Havar - 5th Anniversary LCC

Investigated Composite Load Introduction Structures in Aircraft

CFRP Rear Link

A340 CFRP Spoiler

Composite

4-Bar Linkage

Flap Support

CRFP Flap Load Introduction Rib

Innovative Flap Load Introductions

11.09.2014 3


Flap

LIR

Aircraft Structures:

• Continuous development of aircraft structures

• Increased use of composite materials

• Composites currently used in frame structures

• Metallic Load Introductions

High Lift System – Composite Flap:

• Composite skin with stringers

• Composite ribs and Spars

• Except metallic load introduction rib

Aim: Innovative composite design for Load Introduction Rib (LIR)

A330 / A340


Aim of Project:

• Redesign of metallic LIR => innovative composite LIR

• Requirements:

• Equal design space, attachments,…

• Load transmission from flap track into flap

• Resistance against temperature, humidity, chemicals,…

11.09.2014 4


Composite Flap

Metal - LIR

Flap Structure

Project Goals:

• Innovative composite design (No black metal!)

• Low manufacturing costs

• Low weight

• High robustness => low maintenance costs

Composite LIR

Project Team:

• Airbus Group Innovations

• Airbus (Lead)

• Airbus Helicopter

• Airbus Defense and Space & Premium AEROTEC

• IVW Kaiserslautern


New Composite Textile Preform Design

11.09.2014 5


DS Rib

DS Bracket

LIR FS Attachment

SL Attachment

RL Attachment

RS Attachment


Design Process

11.09.2014 6


Modification of

exist. Flap FEM

New Design of

LIR (CAD)

New FEM

Model of LIR Integration of

LIR Model in

Flap Model

Integration of

Rivets

Part C

Part B

Part A

Application of

Loads

Analysis of

Stresses


3D Sizing with effects of defects

• Plies milled (Waviness => too thick)

• Fiber orientation taken from pre-form

11.09.2014 7


3

Results of Analysis

• Successful Sizing of LIR

• Few critical points

• Local small Reserve Factors (RF) dependent on load case

•Fiber compression S11min

•Matrix tension S22max

• No critical delaminations calculated S12, S13 und S23

• No matrix crack at gusset fillers

1

2 2

1 2

3


Manufacturing (Airbus Helicopters)

11.09.2014 8


Preforming of Parts

• Automated NCF Cut Out

• Positioning of Load Introduction

• Draping of Rib Layers

• Precompatcting

• Adding of Reinforcement Layers

• 3D Stitching of Edges

• 3D Cutting of Edges

• Automated Pre-form QS


Manufacturing (Premium Aerotec)

11.09.2014 9


Infiltrated Parts

• LIR with CFRP Lugs

• 3D Reinforcement

• Drive Ribs

• Drive Bracket

• Pi Profiles

• FS-Attachments

• Aux Spar


Manufacturing (Airbus)

11.09.2014 10


Assembly

• Shortening of A340 OB Flap

• Reinforcement of Lower Skin

• Assembly of LIR

• Assy. DS Rib and Bracket

• Assy. Clamping Ribs

Top View Bottom View


Validation (Premium Aerotec)

11.09.2014 11


Testing of 5 Critical Load Cases

•Testing of Flap with integrated LIR

• BVID (Barely Visible Impact Damage)

• VID (Visible Impact Damage)

• NDI after Damages

• Static Loads partly with EKDF

• Fatigue Loads with LEF

BVID + NDI VID + NDI

Fatigue Phase, LEF 1,15 Damage Tolerance

Phase

3 Actuators 80 Strain gauges


Validation (Premium Aerotec)

11.09.2014 12


Finished Testing

• Small Delamination of Gusset Filler of DS Bracket

• Possible Delamination in inner LIR Radius

• Loads were carried despite small damages

• Fatigue Testing without further damages


Summary LIR

11.09.2014 13


Design and Sizing

• New Innovative Composite Design of Flap Load Introduction Rib

• Ability to analyze complex 3D Composite Parts

• Integration of effects of defects into sizing

Verification

• Verification with Risk Reduction Articels Spring Back etc.

• Verification of Preforming Abilities of all Parts

• Curing of Load Introduction Ribs with VAP Process

• QS of finished Parts

Validation

• Integration of LIR in existing A340 outbaord flap

• Fatigue and damage tolerance Testing

Over 25% Weight Reduction

Over 5% Cost Reduction

Further Investigations

CFRP Lug Sizing Rules

11.09.2014 14


Motivation

• Increased use of composites in current high-lift lightweight designs

• Mostly extensive testing needed for new structural components

• => Costly: most critical several load cases are to be tested

• There are only few guidelines / designers experience

• More general approach from specific part towards common design

guidelines for high-lift structures are needed

11.09.2014 15


Comparison between FEA and Test for Composite Lugs

0

50

100

150

200

250

300

350

400

450

500

1.2 1.4 1.6 1.8 2 2.2

Radius Ratio ra/ri

Fo

rce

[kN

]

FEA: QI FF

Test: QI FF

Test: QI IFF

FEA: QI IFF

Fiber Failure

Inter-Fiber Failure

Aim: General Design Rules for Lugs and Loops


Approach

• Analysis of composite load introductions

(analytical and FEA)

• Validation of composite lugs and loops

• First Ply Failure / Residual Strength

11.09.2014 16


Failure Load Verification of Laminates with Lug

under 0° Loading

Test vs. FEM and Analytical Calc.

0

50

100

150

200

250

300

350

400

450

500

1,3 1,4 1,5 1,6 1,7 1,8 1,9 2

Ratio of Radius: ra/ri [ ]

Fail

ure

Lo

ad

[K

N]

Test-Lug-Failure

FEM-Lug-Failure

Analyt-Lug-Failure

Test-Lug-Non Linear

FEM-Lug-First Failure

Analyt-Lug-First Failure

Parameter study at 0° Loading

Lug vs. Loop (with and without inner ring)

0

100

200

300

400

500

600

700

1 1,1 1,2 1,3 1,4 1,5 1,6 1,7 1,8 1,9 2

Ratio of Diameter: Da/Di [ ]

Fail

ure

Lo

ad

[K

N]

FEM-Loop-Innerring-Failure

FEM-Loop-Failure

FEM-Lug-Failure

Test-Lug-Failure

0° Loading:

Loops better performance:

=> Fiber in load direction

Lugs low performance:

=> Fiber cut in load direction Parameter study at 90° Loading

Lug vs. Loop (with and without inner ring)

0

50

100

150

200

250

300

1 1,1 1,2 1,3 1,4 1,5 1,6 1,7 1,8 1,9 2

Ratio of Diameter: Da/Di [ ]

Fail

ure

Lo

ad

[K

N]

FEM-Loop-Innerring-Failure

FEM-Loop-Failure

FEM-Lug-Failure

90° Loading:

Loops low performance:

=> Matrix in load direction

Lugs low performance:

=> Fiber partly in load direction


Progressive Failure Analysis of Lugs and Loops

=> AIM: Virtual Testing of Composite Lugs and Loops

• Damage Initiation using 3D Puck

• Damage evolution: failure mode dependent

– Gradual softening for inter-fiber fracture

Stiffness degradation (not E║) depending on failure mode

– Instantaneous degradation for fiber fracture, representing total structural failure

• Coupling of Fortran subroutine (including 3D Puck and degradation scheme) within every

incremental calculation of nonlinear simulation

11.09.2014 17


Analysis at every integration point

Evaluation in layers possible FF

IFF,

IFF,

0n

0n


Scientific Approach (by Carolin Werchner)

11.09.2014 18


0

1000

2000

3000

4000

5000

6000

0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4

Increments

Sh

ea

r m

od

ulu

s G

12 [

N/m

m2]

IFF FF

softening factor h degraded shear modulus G12

Verification of gradual and instantaneous

stiffness degradation

Comparison Strain Distribution:

Test vs. FEA

Test FEA

Comparison Fracture Mode

Very good qualitative accordance

But strong calibration needed

(mesh dependency etc.)

0

0.2

0.4

0.6

0.8

1

0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4

Increments

So

fte

nin

g f

ac

tor

h

IFF FF

Further Investigations

Next Applications

11.09.2014 19

Next Applications

Basis: Composite 4 Bar Linkage Flap Support

• Replacement of metal carriage

• Full Composite Linkage System

• Linkages

• Brackets

• Linkages mostly as composite loops

• Lugs: thick laminate load introduction

• Failure case reduction:

• No jam of carriage

• Linkages with bearings

• Maintenance reduction

• No ball bearings

• Self lubricant bearings

• Major weight reduction

11.09.2014 20


WingFlap

Metal Track Rear Link Kinematics

Composite 4 Bar Linkage Kinematics

Next Applications

Innovative High Lift Systems for Future Aircraft

11.09.2014 21


Questions?

Thank You!

11.09.2014 22

load introduction into aerospace structures€¦ · load introduction into aerospace structures ......

Documents